Driving force transmitting device and image forming apparatus including the same

Abstract

A driving force transmitting apparatus includes a driving source, a drive pulley rotatable by a driving force supplied from the driving source, a follower pulley rotatable with a member to be rotated, and a belt member extending around a cylindrical surface of the driving pulley and a cylindrical surface of the follower pulley. In addition, an intermediate transmission member contacts the driving pulley and the follower pulley, and the intermediate transmission member has a rigidity higher than that of the belt member.

What is claimed is: 
     
       1. A driving force transmitting apparatus comprising:
 a driving source; 
 a drive pulley rotatable by a driving force supplied from said driving source; 
 a follower pulley rotatable with a member to be rotated; 
 a belt member extending around a cylindrical surface of said driving pulley and a cylindrical surface of said follower pulley; and 
 an intermediate transmission member which contacts said driving pulley and said follower pulley, wherein said intermediate transmission member has a rigidity higher than that of said belt member. 
 
     
     
       2. An apparatus according to  claim 1 , wherein said belt member is extended around said intermediate transmission member so that a tension of said belt member urges said intermediate transmission member in a direction of pushing said intermediate transmission member between said driving pulley and said follower pulley. 
     
     
       3. An apparatus according to  claim 1 , further comprising an urging member for urging said intermediate transmission member between said driving pulley and said follower pulley. 
     
     
       4. An apparatus according to  claim 1 , wherein an outer diameter of the cylindrical surface of said follower pulley is larger than an outer diameter of the cylindrical surface of said driving pulley. 
     
     
       5. An apparatus according to  claim 1 , wherein said belt member is a metal belt. 
     
     
       6. An apparatus according to  claim 1 , further comprising rotational speed detecting means for detecting a rotational speed of said follower pulley, and control means for controlling a rotational speed of said driving pulley on the basis of an output signal of said rotational speed detecting means. 
     
     
       7. An image forming apparatus comprising an image bearing member, toner image forming means for forming a toner image on said image bearing member, and a driving force transmitting apparatus according to  claim 1  for driving said image bearing member, which is the member to be rotated. 
     
     
       8. A driving force transmitting apparatus comprising:
 a driving source; 
 a drive pulley rotatable by a driving force supplied from said driving source; 
 a follower pulley rotatable with a member to be rotated; 
 a belt member extending around a cylindrical surface of said driving pulley and a cylindrical surface of said follower pulley; and 
 an intermediate transmission member which is arranged with a part of said belt member interposed directly between said driving pulley and said intermediate transmission member and with a part of said belt member interposed directly between said intermediate transmission member and said follower pulley, wherein said intermediate transmission member has a rigidity higher than that of said belt member. 
 
     
     
       9. An apparatus according to  claim 8 , wherein said belt member is extended around said intermediate transmission member so that a tension of said belt member urges said intermediate transmission member in a direction of pushing said intermediate transmission member between said driving pulley and said follower pulley. 
     
     
       10. An apparatus according to  claim 8 , further comprising an urging member for urging said intermediate transmission member between said driving pulley and said follower pulley. 
     
     
       11. An apparatus according to  claim 8 , wherein an outer diameter of the cylindrical surface of said follower pulley is larger than an outer diameter of the cylindrical surface of said driving pulley. 
     
     
       12. An apparatus according to  claim 8 , wherein said belt member is a metal belt. 
     
     
       13. An apparatus according to  claim 8 , further comprising rotational speed detecting means for detecting a rotational speed of said follower pulley, and control means for controlling a rotational speed of said driving pulley on the basis of an output signal of said rotational speed detecting means. 
     
     
       14. An image forming apparatus comprising an image bearing member, toner image forming means for forming a toner image on said image bearing member, and a driving force transmitting apparatus according to  claim 8  for driving said image bearing member, which is the member to be rotated.